When creating a list and not specifying SortOrder, it gives a sort order of -1. This seems to mess up and makes that newly created list the default (or atleast that is how it behaved for me).
Also, I seem to be able to give same SortOrder to multiple lists. What I am lost on is why is SortOrder required. And when I don't specify SortOrder, why doesn't it give a number in order of how many lists there exist. Why does a end-user of your api have to deal with it?
SortOrder is used only to control the order in which the lists display in our web UI. This is no way impacts sign up forms, defaults or anything else with any of our other products.
Your feedback on the default behavior is great and something we're looking at as we're enhancing our API features. Would having this be an optional field and, if left out, default to the next numerical value of the lists automatically be the behavior you'd expect and want? If not, please provide some additional information on how you'd expect it to perform.